UN 2393 — Isobutyl formate
Placard: Flammable. ERG Guide 129. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2393 is Isobutyl formate, a flammable ester liquid assigned to ERG Guide 129. Heavy vapors can travel to ignition sources and flash back.
Hazard overview: FLAMMABLE ester liquid; vapors may ignite and form explosive mixtures with air. Vapors are heavier than air and may travel to ignition sources and flash back. Vapor explosion hazard exists in low areas, drains, sewers and confined spaces.
Response guidance: For UN 2393, isolate the area, eliminate ignition sources, keep vapors out of drains and use SCBA in vapor or fire conditions. Cool containers from a protected distance and choose foam, dry chemical or CO2 using SDS and ERG 129.
Firefighter training notes: Training for UN 2393 should emphasize vapor travel, low-area accumulation, sewer flashback, foam selection, ignition control, container cooling and vapor monitoring. Use ERG 129, SDS and local SOP.
Regulatory context: Isobutyl formate is regulated as a hazardous material for transport and emergency response. Storage, exposure, spill reporting, waste and fire-code duties depend on quantity, concentration and jurisdiction; verify shipping papers, SDS and local authority requirements.
Storage & handling: Isobutyl formate should be stored in approved flammable-liquid containers with ventilation, bonding/grounding where required, spill containment and separation from heat, ignition sources, oxidizers and incompatible materials.
UN 2393 Quick Details
Common Hazards of UN 2393
- FLAMMABLE ester liquid; vapors may ignite and form explosive mixtures with air.
- Vapors are heavier than air and may travel to ignition sources and flash back.
- Vapor explosion hazard exists in low areas, drains, sewers and confined spaces.
- Liquid may float on water or form a separate layer, spreading fire or contamination.
- Runoff to sewers may create fire or explosion hazards.
- Fire may produce carbon monoxide and irritating/toxic smoke.
- Containers may rupture or explode when heated.
Chemical Identity & Physical Properties
Clear colorless liquid with a fruity, rum-like odor. Volatile and less dense than water.
| Also known as | Formic acid isobutyl esterIsobutyl methanoate2-Methylpropyl formateHCOOCH2CH(CH3)2 |
| CAS Number | 542-55-2 |
| Appearance | Clear colorless liquid with a fruity, rum-like odor. Volatile and less dense than water. |
| Flash Point | -6C (21F) |
| Boiling Point | 98C (208F) |
| Vapor Density | 3.5 (heavier than air) |
| Water Reactivity | No significant reaction; slightly soluble in water, floats on surface |
Fireground Response Guidance — UN 2393
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, fire or confined-space exposure. Wear chemical-resistant gloves, eye/face protection and flame-resistant protection as appropriate.
Isolation & Evacuation
First Actions for a UN 2393 Incident
- Call 911 and the emergency response number on the shipping paper, if available.
- Keep unauthorized personnel away and establish incident command.
- Stay upwind, uphill and upstream; keep responders out of low vapor areas.
- Eliminate ignition sources if this can be done safely.
- Avoid breathing vapor, mist or smoke and avoid skin or eye contact.
- Do not touch damaged containers or spilled material without proper training and PPE.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 129, SDS, shipping papers and air monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2393 — Isobutyl formateUse for: Quick radio or face-to-face size-up. Short, structured, field-ready.
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
Use for: Quick text to command or incoming units. Fits in a single SMS.